Developing cartridge that includes member to be pressed by image-bearing-member cartridge

Abstract

A process cartridge includes an image bearing member cartridge and a developing cartridge detachably installed in the image bearing member cartridge. The image bearing member cartridge has a pair of first and second side plates, a latent image bearing member, and a pressure member. The developing cartridge has a pair of third and fourth side plates and a pair of first and second light guides fixed at the third and fourth side plates, respectively. The pressure member presses side surfaces of the first and the second light guides, thereby urging the developing agent bearing member toward the latent image bearing member.

1. A process cartridge detachably installable to a main frame of an image forming device, the main frame having a developing-agent amount detection unit including a light emitting element and a light receiving element, comprising:
 an image bearing member cartridge including:
 a first casing having a pair of first and second side plates defining an accommodation portion; 
 a latent image bearing member having a surface on which an electrostatic latent image is formed, the latent image bearing member being supported to the first casing; and
 a pressure member; and 
 
 a developing cartridge detachably installed in the accommodation portion and including:
 a second casing having a pair of third and fourth side plates in confrontation with the first and second side plates, respectively, the pair of third and fourth side plates defining a chamber that stores a developing agent; 
 a developing agent bearing member rotatably supported to the second casing, the developing agent bearing member supplying the developing agent onto the latent image bearing member; and 
 a pair of first and second light guides fixed to the third and fourth side plates, respectively, the pair of first and second light guides being configured to introduce a light emitted from the light emitting element into the chamber and to direct the light from the chamber toward the light receiving element, each of the first and second light guides having a fixed end portion having a first end surface and fixed to either of the third and fourth side plates, a free end portion having a second end surface and remote from the chamber, and a side surface extending in an axial direction of the developing agent bearing member, wherein: 
 
 the pressure member presses the side surfaces, thereby urging the developing agent bearing member toward the latent image bearing member. 
 
 
     
     
       2. The process cartridge according to  claim 1 , wherein:
 the developing cartridge further includes a gear transmission mechanism provided at the third side plate, the gear transmission mechanism transmitting a driving force to the developing agent bearing member; and 
 a distance between the third side plate and the second end surface of first light guide is greater than a distance between the third side plate and an outer contour of the gear transmission mechanism. 
 
     
     
       3. The process cartridge according to  claim 1 , wherein the pair of first and second light guides are made from a transparent material. 
     
     
       4. The process cartridge according to  claim 1 , wherein the pair of first and second light guides are positioned in symmetrical relationship with each other with respect to a plane extending in a direction perpendicular to the axial direction of the developing agent bearing member. 
     
     
       5. The process cartridge according to  claim 1 , wherein each of the first and second light guides is bent and has a part that extends in a direction parallel to the second side plates. 
     
     
       6. The process cartridge according to  claim 1 , wherein each of the first and second light guides includes a window disposed at either of the third and fourth side plates and a hollow cylindrical projection projecting from the either of the third and fourth side plates and surrounding an outer periphery of the window, the hollow cylindrical projection having the side surface. 
     
     
       7. The process cartridge according to  claim 1 , wherein each of the first and second side plates is formed with a recess having a top opening, the recess receiving therein either of the first and the second light guides. 
     
     
       8. The process cartridge according to  claim 1 , wherein a distance between the third side plate and the second end surface of the first light guide is greater than a distance between the third side plate and the first side plate. 
     
     
       9. A developing cartridge detachably installable in an image bearing member cartridge including a pressure member, comprising:
 a cartridge casing having a pair of first and second side plates defining a chamber that stores a developing agent; 
 a developing agent bearing member bearing the developing agent supplied from the chamber, the developing agent bearing member rotatably supported to the cartridge casing; and 
 a pair of first and second light guides fixed to the first and second side plates, respectively, the pair of first and second light guides being configured to introduce a light into the chamber and directing the light from the chamber, wherein: 
 the first light guide has a fixed end portion fixed to the first side plate and a free end portion remote from the chamber; 
 the free end portion has an end surface and a side surface that the pressure member of the image bearing member cartridge presses, 
 wherein each of the first and second light guides includes a window disposed at either of the first and second side plates and a hollow cylindrical projection projecting from the either of the first and second side plates and surrounding an outer periphery of the window, the hollow cylindrical projection having the side surface. 
 
     
     
       10. The developing cartridge according to  claim 9 , further comprising a gear transmission mechanism provided at the first side plate, the gear transmission mechanism transmitting a driving force to the developing agent bearing member, wherein a distance between the first side plate and the end surface is greater than a distance between the first side plate and an outer contour of the gear transmission mechanism. 
     
     
       11. The developing cartridge according to  claim 9 , wherein the pair of first and second light guides are made from a transparent material. 
     
     
       12. The developing cartridge according to  claim 9 , wherein the pair of first and second light guides are positioned in symmetrical relationship with each other with respect to a plane extending in a direction perpendicular to an axial direction of the developing agent bearing member. 
     
     
       13. A developing cartridge detachably installable in the image bearing member cartridge including a pressure member and a latent image bearing member, comprising:
 a cartridge casing having a pair of first and second side plates defining a chamber that stores a developing agent; 
 a developing agent bearing member bearing the developing agent supplied from the chamber, the developing agent bearing member rotatably supported to the cartridge casing; 
 a gear transmission mechanism provided at the first side plate, the gear transmission mechanism transmitting a driving force to the developing agent bearing member; and 
 a pair of first and second light guides fixed to the first and second side plates, respectively, the pair of first and second light guides being made from a transparent material and configured to introduce a light into the chamber and directing the light from the chamber, the pair of first and second light guides being positioned in symmetrical relationship with each other with respect to a plane extending in a direction perpendicular to an axial direction of the developing agent bearing member, wherein:
 the first light guide has a fixed end portion fixed to the first side plate and a free end portion remote from the chamber; 
 the free end portion has an end surface and a side surface that the pressure member of the image bearing member cartridge presses, the free end being configured to urge the developing agent bearing member toward the latent image bearing member when the pressure member presses the end surface and side surface; and 
 a distance between the first side plate and the end surface is greater than a distance between the first side plate and an outer contour of the gear transmission mechanism. 
 
 
     
     
       14. A developing cartridge comprising:
 a cartridge casing having a pair of first and second side plates defining a chamber that stores a developing agent; 
 a developing agent bearing member bearing the developing agent supplied from the chamber, the developing agent bearing member rotatably supported to the cartridge casing; and 
 a pair of first and second light guides fixed to the first and second side plates, respectively, the pair of first and second light guides being configured to introduce a light into the chamber and directing the light from the chamber, wherein: 
 the first light guide has a fixed end portion fixed to the first side plate and a free end portion remote from the chamber; 
 the free end portion has an end surface and a side surface, 
 wherein each of the first and second light guides includes a window disposed at either of the first and second side plates and a hollow cylindrical projection projecting from the either of the first and second side plates and surrounding an outer periphery of the window, the hollow cylindrical projection having the side surface. 
 
     
     
       15. The developing cartridge according to  claim 14 , further comprising a gear transmission mechanism provided at the first side plate, the gear transmission mechanism transmitting a driving force to the developing agent bearing member, wherein a distance between the first side plate and the end surface is greater than a distance between the first side plate and an outer contour of the gear transmission mechanism. 
     
     
       16. The developing cartridge according to  claim 14 , wherein the pair of first and second light guides are made from a transparent material. 
     
     
       17. The developing cartridge according to  claim 14 , wherein the pair of first and second light guides are positioned in symmetrical relationship with each other with respect to a plane extending in a direction perpendicular to an axial direction of the developing agent bearing member.